site: owner-only dashboard link in header, mobile menu and homepage (g then d from any page); /start skips the site chrome JS

- Header/footer moved to #lib/components/SiteChrome.svelte, returned by a universal
  +layout.ts load only for non-immersive pages, so /start and the book reader never
  download icon libraries, dropdowns or the bits-ui Sheet. /start: 36 -> 18 JS files,
  133 -> 78 KB gzip.
- Header logo is a hashed asset (inlined), so it is cached with the build.
- inlineStyleThreshold 4096: tiny page/component CSS is inlined into the HTML.
- Umami is not loaded on /start.

src/lib/chrome.ts

@@ -0,0 +1,19 @@
+/**
+ * Full-screen pages that render without the site header and footer: the /start new-tab
+ * dashboard and the book reader. They also skip loading the header's JS (icons, menus,
+ * the mobile Sheet): src/routes/+layout.ts only imports SiteChrome for other pages.
+ */
+export function isImmersive(pathname: string): boolean {
+	return /^\/start\/?$/.test(pathname) || /^\/trackers\/books\/\d+\/read\/?$/.test(pathname);
+}
+
+/** True when a keyboard shortcut should not fire because the user is typing. */
+export function isTyping(target: EventTarget | null): boolean {
+	if (!(target instanceof HTMLElement)) return false;
+	return (
+		target.isContentEditable ||
+		target.tagName === 'INPUT' ||
+		target.tagName === 'TEXTAREA' ||
+		target.tagName === 'SELECT'
+	);
+}